use std::{
    cell::{RefCell, RefMut},
    os::raw::c_void,
};

use cocoa::base::id;
use objc::{
    declare::ClassDecl,
    runtime::{Class, Object, Sel},
};
use once_cell::sync::Lazy;

use crate::{platform::macos::ActivationPolicy, platform_impl::platform::app_state::AppState};

static AUX_DELEGATE_STATE_NAME: &str = "auxState";

pub struct AuxDelegateState {
    pub activation_policy: ActivationPolicy,
    pub default_menu: bool,
}

pub struct AppDelegateClass(pub *const Class);
unsafe impl Send for AppDelegateClass {}
unsafe impl Sync for AppDelegateClass {}

pub static APP_DELEGATE_CLASS: Lazy<AppDelegateClass> = Lazy::new(|| unsafe {
    let superclass = class!(NSResponder);
    let mut decl = ClassDecl::new("WinitAppDelegate", superclass).unwrap();

    decl.add_class_method(sel!(new), new as extern "C" fn(&Class, Sel) -> id);
    decl.add_method(sel!(dealloc), dealloc as extern "C" fn(&Object, Sel));

    decl.add_method(
        sel!(applicationDidFinishLaunching:),
        did_finish_launching as extern "C" fn(&Object, Sel, id),
    );
    decl.add_ivar::<*mut c_void>(AUX_DELEGATE_STATE_NAME);

    AppDelegateClass(decl.register())
});

/// Safety: Assumes that Object is an instance of APP_DELEGATE_CLASS
pub unsafe fn get_aux_state_mut(this: &Object) -> RefMut<'_, AuxDelegateState> {
    let ptr: *mut c_void = *this.get_ivar(AUX_DELEGATE_STATE_NAME);
    // Watch out that this needs to be the correct type
    (*(ptr as *mut RefCell<AuxDelegateState>)).borrow_mut()
}

extern "C" fn new(class: &Class, _: Sel) -> id {
    unsafe {
        let this: id = msg_send![class, alloc];
        let this: id = msg_send![this, init];
        // TODO: Remove the need for this initialization here
        (*this).set_ivar(
            AUX_DELEGATE_STATE_NAME,
            Box::into_raw(Box::new(RefCell::new(AuxDelegateState {
                activation_policy: ActivationPolicy::Regular,
                default_menu: true,
            }))) as *mut c_void,
        );
        this
    }
}

extern "C" fn dealloc(this: &Object, _: Sel) {
    unsafe {
        let state_ptr: *mut c_void = *(this.get_ivar(AUX_DELEGATE_STATE_NAME));
        // As soon as the box is constructed it is immediately dropped, releasing the underlying
        // memory
        Box::from_raw(state_ptr as *mut RefCell<AuxDelegateState>);
    }
}

extern "C" fn did_finish_launching(this: &Object, _: Sel, _: id) {
    trace_scope!("applicationDidFinishLaunching:");
    AppState::launched(this);
}